1. Field of Invention
The present invention relates to a manufacturing method of a semiconductor device, and particularly to a method for manufacturing a semiconductor device in which an element forming layer is peeled off a supporting substrate by using a peeling layer provided between the supporting substrate and the element forming layer.
2. Description of the Related Art
In recent years, the necessity of a card mounting an RFID (Radio Frequency Identification) or a tag mounting an RFID which can transmit and receive data without contact has been increased in any fields which need automatic identification such as management of valuable securities and merchandise. The card mounting an RFID reads and writes data from/to an external device via a loop antenna in the card without contact. The card mounting an RFID has larger memory capacity and higher security than a magnetic card that records data by a magnetic recording method. Hence, a mode of the card mounting an RFID applicable to various fields has been proposed recently.
In general, an RFID is constituted by an antenna and an IC chip which is formed of an element forming layer including a transistor group and the like provided over a silicon wafer. In recent years, however, even lower cost and an even thinner type are desired and technological development of an RFID using an element forming layer provided over a glass substrate or the like has been advanced. Furthermore, technological development for reducing the thickness of a substrate part of an element forming layer provided over a glass substrate, or peeling an element forming layer from a glass substrate and transferring it to another supporting substrate has been advanced. Various techniques have been contrived as a method for these.
For example, there are a method of taking out an element forming layer by making a supporting substrate thin by grinding or polishing, a method of removing a supporting substrate by chemical reaction and the like, a method of peeling an element forming layer from a supporting substrate, and the like. As a method of peeling an element forming layer provided over a supporting substrate, for example, there is a known technique that a separating layer formed of amorphous silicon (or polysilicon) is provided, and hydrogen contained in amorphous silicon is released by laser light irradiation through a substrate, thereby a space is generated to separate the supporting substrate (see Patent Document 1). In addition, there is a technique that a peeling layer containing silicon is provided between an element forming layer and a supporting substrate, and the peeling layer is removed by using a gas containing halogen fluoride to separate the element forming layer from the supporting substrate (see Patent Document 2). As described above, there are many methods for separating an element forming layer provided over a supporting substrate.    [Patent Document 1] Japanese Patent Laid-Open No. Hei 10-125929    [Patent Document 2] Japanese Patent Laid-Open No. Hei 8-254686
However, the methods of removing a supporting substrate by grinding, polishing, or dissolving cause problems like damage due to physical strength such as stress and vibration, and contamination. Furthermore, according to such methods, it is quite difficult to reuse a substrate and the cost is increased.
In the case where an element forming layer provided over a supporting substrate is separated by removing a peeling layer provided between the supporting substrate and the element forming layer, the quality of the peeling layer becomes important. That is, time required for removing the peeling layer is affected by a material used for the peeling layer and an etchant used for removing the peeling layer. In addition, in the case where an element forming layer constituted by a thin film transistor and the like is provided over a peeling layer, the property of the transistor may be affected and the reliability of a semiconductor device may be decreased depending on a material or the film quality of the peeling layer.